Prevalence of externalized conductors in Riata and Riata ST silicone leads: Results from the prospective, multicenter Riata Lead Evaluation Study

BACKGROUND/OBJECTIVE Following a class I recall of St. Jude Medical Riata/Riata ST silicone implantable cardioverter-defibrillator leads, we report on the phase I results of the Riata Lead Evaluation Study, a prospective, multicenter investigation to assess the prevalence of externalized conductors (ECs) and the electrical dysfunction in these leads. METHODS We enrolled patients previously implanted with Riata/Riata ST leads and performed cinefluoroscopy using multiple views. A physician panel adjudicated the images for the presence of EC. The prevalence of EC was stratified and compared by lead model and patient characteristics. Upon occurrence of a lead revision, another physician panel determined whether electrical dysfunction had occurred based on predefined criteria. RESULTS Seven hundred seventy six patients with Riata/Riata ST silicone Leads (8Fr/7Fr = 66.6%/33.4%; single-/dual-coil = 12.9%/87.1%) across 23 centers were analyzed. Implant duration was 4.8 +/- 0.9 years for 7Fr and 6.5 +/- 1.6 years for 8Fr leads (P < .001). The prevalence of EC was significantly lower in 7Fr compared with 8Fr leads for the entire study population (9.3% vs 24.2%, P < .001) and for Leads implanted <= 6 years (9.4% vs 18.8%, P = .006). Other than Lead size, there were no significant differences in lead, patient, or electrical characteristics between leads with and without EC. Over a period of 9.8 +/- 2.0 months, the overall prevalence of electrical dysfunction was 1.3% (confidence interval 0.49%-2.1%), with only 3 of 10 cases occurring in leads with EC. CONCLUSION Larger-diameter Riata Leads were more prone to EC than smaller-diameter Riata ST leads. The prevalence of electrical dysfunction was not associated with EC.